For eight minutes, the city of Washington, DC, was at a red terror alert level, the first time the highest alert level had been issued since the system was put into place, the Department of Homeland Security reported.

Sheaffer held his course even after being told to leave the area, but eventually diverted his aircraft after military jets fired four warning shots across his plane’s nose, The Associated Press reported.

Sheaffer and Martin were released after being detained for questioning. Officials said the pair was simply lost and confused.

“They were navigating by sight and were lost,” Justice Department spokesman Kevin Madden told The AP.

Other officials said Sheaffer was out of practice and shouldn’t have been flying in the first place. FAA examiner Mike Kuhn told the Lancaster Intelligencer Journal that Sheaffer, 69, had approached him earlier in the day, asking for help to refuel his plane.

“He hadn’t been out there in so long, he didn’t know how to operate the pumps,” Kuhn told the Intelligencer Journal. “The people who fly into restricted areas are the people who don’t come to safety meetings and don’t have what they need when it comes to training.”

Friends of Shaeffer, however, said this was an easy mistake to make.

“It’s awfully easy for this to happen to anyone,” John E. Henderson, who was in the same flight club as Shaeffer, told The AP. “It’s just a shame that it happened to this guy, because he is one swell guy.”